The most important thing the beginning water gardeners and new pond owners tend to overlook when setting up a water feature is, how many gallons does it holds? I was no exception, mainly because I did not know any better. After it is all put together we cannot take the water out and start new, this would not be very practical, but to know how many gallons the pond holds is very important. Keep in mind as we create an artificial ecosystem, something nature would need many years to accomplish; we need to add certain chemicals to make it all work. If we like to add fish, we need to make the tap- or well water safe for them and we will have to use some water conditioners. To rid the water of the fish waste and to prevent excess algae, we need to add artificial bacteria. Every one of these products comes with an instruction to use so and so much in so and so many gallons. Now what? The pond is filled and we have no clue how many gallons it holds. There is a simple formula to figure this out. Of course it will never be completely exact but close enough.

Here it is:
Rectangular ponds: Length x width x depth = number of cubic feet
There are 7.5 gallons of water per cubic feet, therefore multiply 7.5 x number of cubic feet = number of gallons
Circular ponds: 3.14 x ½ diameter x ½ diameter x depth = number of cubic feet x 7.5 = number of gallons

In all cases vertical sides and level bottoms are assumed. With sloping sides or plant shelves the numbers are not quite accurate. The best solution is to buy a water meter and use it on the water hose when filling the pond. You can buy such a devise for under $ 10 plus shipping by calling:
1 866-H20WATCH

Stocking formula for a balanced pond:
Two bunches of submerged (oxygenating) plants per square yard of pond surface. One water lily for each square yard of surface area or enough floating plants to cover 60-70 % of pond surface during summer. Two inches of fish (length) for each square foot of pond surface in a pond 18 to 24 inches deep, or one Koi for each 25 square feet. Eight to ten small snails, optional. Or a little easier to work out, 1 goldfish for 30 gallons and one Koi for 125 gallons in a pond containing more than 1000 gallons.